Electrical receptacle



P 1933- H. J. GRAHAM 1,927,638

ELECTRICAL RECEPTACLE Filed April 25. 1928 M67220?" HERBERT J. GRAHAM J Patented Sept. 19, 1933 UNITED STATES PATENT o l-C ELECTRICAL RECEPTACIIE r Herbert J. Graham, Philadelphia, Pa assignor to Electric Service Supplies Company, Philadelphia, Pa., a..corpration of Pennsylvania Application April 25,1928. Serial Nae-12,729 6 Claims. (01. 179-356) center contacts of the lamp and socket and at the socket terminals when the lamp socket is subjected to vibration and other shocks incidental to its use.

. It hasbeen found that in the usual type of 10 lamp socket the tendency has been for the lamp provision of a gripping device in association with a lamp socket, said device being so arranged with to back-out or become loosened when the socket is subjected to undue vibrations, shocks or jars, this difiiculty being especially noticeable in those instances where the lamp socket is used in connection with locomotive headlights. Continual loosening of the lamp within its socket soon-results in an uncertain electrical contact between the center contacts of the lamp and socket with the consequence that a destructive and dangerous arcing condition is established between said center contacts. This same destructive arcing condition often arises at the socket terminals when the latter become loosened due to excessive vibration of the socket. Various expedients have been. resorted to fromtime to time with a view to obviating these troubles, but none of them have been particularly successful. In certain cases the sockets were so designed that it became difficult to remove the lamp when it was desired to do so. In other cases, the socket constructions were not of sufficient strength andrigidity to meet the present strict requirements, while in still other cases their general use was prohibited because they were either too complicated or too ex-' pensive to manufacture.

,It is accordingly among the principal objects of this invention to provide a lamp socket having means for securely gripping the base of a lamp to effectually prevent any tendency of the latter to either vibrate or become loosened in the.

socket, said means being simple and efficient in use at the same time that it is capable of being readily applied to the socket without impairing the strength and rigidity of the latter.

A still further objectof the invention is the respect to said socket that the lamp base is firmly gripped immediately as it is threaded into the socket. By reason of this arrangement, it will be apparent that when the lamp base is threaded into the socket so that the center contacts thereof are in firm contact the basewill be gripped at a point removed from its inner end, that is, at a point adjacent the lamp receiving end of the socket. In consequence of the fact that this gripping action takes place at the outer end of the socket, it becomes difficult, if not entirely impossible, for one to shift the lamp laterally with respect to the socket in order to obtain better focusing thereof. This practice of obtaining better focus by shifting the lamp within its socket rather than by making an adjustment of thelat ter often results not only in injury to the lamp but ininjury to the socket as well.

A still further object of this invention is the provision of a pair of spring pressed devicesfor frictionally engaging opposite sides of a lamp base, these devices being so constructed as to afford a broad frictional engagement to be had against the thread of the lamp base, this engagement being such that the-thread is reformed during the operation of threading the lamp base into its socket. The effect of this isto provide amuch closer fit between the lamp base and its socket than is ordinarily had, yet the arrangement does not interfere with the ready withdrawal of l the lamp from its socket when. desired.

1 Aflstill further object of the invention ispthe the socket is subjected to continuousvibration due to the fact that thereis always the possibility of the terminals becoming loosened with the result that the wires either become disconnected entirely from the socket or else become so loosened as to establishthat destructive arcing condition at the terminals which has been found so objectionable; Other objects andobjects relating to details of construction and assembly for effecting economies in the manufacture of the socket will appear more ;fully hereinafter.

' The-invention consists substantially in the construction, combination, location, and relative arrangement of parts, all as will be described more fully hereinafter, as shown in the accompanying drawing, and finally pointed out in'the appended claims.

In the accompanying drawing:

Figure l is aside elevation of a lamp socket embodying the principles of this invention, a lamp being shown inserted within said socket;

Figure 2 is a top plan view of the socket;

Figure 3 is a bottom plan view of the socket;

Figures 4 and 5 are cross sectional views taken on the lines 44 and '55,- respectively, of Figure 2.

Figure 6 is a perspectiveiview showing one of the members for frictionally engaging the base of the lamp; i I

Figures 7 and 8 are perspective views of the terminal members of the socket; e

Figure 9 is a fragmentary view of a lamp show- 2' ing the form which the thread of the lamp base takes when the latter. is inserted. into the socket;

and i Figure 10 is an enlarged plan view of the left hand portion of the socket as shown in Figure 2.

Referring now more particularly to the drawing, it will be seen that the lamp socket. embo.dy-.

ing the principles of this inventioncomprises' a main insulating body or casing 10 hayingra; cen tral recess or socket 11 within which is arranged to be received the threaded shell? 1 21 constituting. one of the contacts forthe lamp. 13., Projecting upwardly from and formed integrally with the bottom wall 14 of the casing 10 is a substantially" U shaped boss 15, the function of which is to divide the upper surface of said bottom wall into separate seats or depressions 1 6 and 17 for receiving, respectively, the contact terminals of the communication with the seat 16, while the open- 7 ing 1 9 communicates with the seat 17. Commun-icating'respectively with said transversely extending openings 18 and 1 9 are the openings 20' and 21 which extend vertically throughthe bottom wall 14- of thecasihg 1 The threaded shell contact 12 within which the lamp base: 22' isarranged to'be threaded is of the form most clearly shown in Figures 4- and 5 wherein it will be seen-"that the bottomand one side thereof are slotted, as at 23,-the'construction of this shell being such that when it is positioned within the insulating casing 10' the upwardly projecting U-shaped boss 15 will project freely through the bottom of said shell. In other words, the arrangement is such that when the screw shell is positioned properly within its 7 lug 26 having a portion thereof struck out, as at casing the bottom thereof will be in embracing relation with respect to said U-shaped boss.

For the purpose of electrically connecting a conducting wire to} the threadedshell contact 12, there is employed a terminal member 24 of the form best shown in Figure '7. This terminal member; which comprises a slotted'portion 25' corresponding in shape to the slotted portion 'of the screw shell 12', is provided with adepending 2'7, to form a loopthrough which thebared end of acon-ducting wire may be inserted. As appears most clearly in Figures 4and 5', the terminal member 24 is arranged between the screw shell '12 and the bottom wall of the casing 10, the lug 26 thereof projecting downwardly toward the bottom of the socket such: that access may be had thereto through the transverse opening 19'. The terminal member 24 is provided with apertures 28, the bottoms of the casing 10' and the screw shell "12 being correspondingly apertured for the passage therethrough' of the securing elements 29. Preferably'these elements are in the form'of rivets; If desired, and it is considered preferable, a reinforcing plate 30 may be inserted 16 is the central terminal member 31 of the form best shown in Fig. 8-, this member being provided with a portion 32"presenting downwardly and toward the transverse opening 18, said portion terminating in a downwardly presenting lug 33 having a struck out portion 34 forming a loop throughwhich the bared end of a second conducting wire may be passed. Access is had to the lug 33 through the'transverse opening 18. Over.-

lying the terminal member 31 is the center spring.

contact. member 35, both of these members being firmly clamped together and to the bottom wall of'the casing 'lOby the securing element 36,

preferably a rivet. The free end 37 of the conin the depression 38, serves to eflectually preclude any tendency for the free end of the center spring contact member to shift laterally out of contact with the center contact of the lamp-base. The conducting wires are permanently attached to the terminal members 24 and 31 of. the socket by means of soldered connections effected after the bared ends of the wires have been inserted through'the loops- 27 and '34 of the terminal members. The openings 18 and 19 in the sides of the socket facilitate the necessary soldering operations. In this connection it is to be understood that while it is-deemed preferable to provide soldered connectionsas herein described, any other form of permanent connection between the terminal members and the conduct- 1 ing wires may be utilized without departing from the general spirit 'ofi'this invention. The arrangement just described not only provides for a strong and durable connection between each terminal member and its respective lamp contacti-ng element, but it also affords a more-permanent connection between each conducting wire and itsrespective terminal member, the result of which is that the possibility of these latter connections becoming loosened when the socket is subjected'to continuous vibration is greatly minimized, if not entirely eliminated.

Destructive arcing conditionsat the socket terminals is thus obviated.

1 In order to eliminate the destructive arcing condition whichoften takes place between the center contacts of the lamp and socket when the latter is subjected to undue vibration, there. is employed in association with the threaded shell contact 12' a pair of "lamp base gripping members 40, one of which is shown in perspective in Figure 6. Each of these members 40? comprises a transversely curved springplate 41 adapted for insertion between the internal suriaceof the casing 10 and the external surface of the shell contact 12. I As appears most clearly in Fig. 4, two plates 41 are employed in diametrically opposed relationfand inasmuch as these. plates are each of a transverse curvature less-than that of the I annular space-withinwhich theyare inserted the plate must be flexed to a greater than their normal curvature, the resulting tendency being for the plates to assume their, normal shape-with the consequence that an inward pressure is ex erted against the external surface of the shell contact 12. Secured adjacent the upper edge of each plate 41 and projecting outwardly from the "concaved surface thereof is a nub 42, preferably of substantially semi-spherical shape, these nubs being arranged to project inwardly and toward each other through suitable apertures 43 formed in opposite sides of the screw shell 12 so as to follow the threads thereof.

The nubs 42 project a sufiicient distance through the apertures 43 in the screw shell so as to afford a firm frictional engagement with the lamp base when the latter is threaded into the socket. In order to insure and obtain a broad frictional engagement between these nubs and the lamp base, the former are of a diameter substantially equal to the pitch of the thread of the lamp base, the pressure which is exerted upon said nubs being sufficient to cause them to reform the lamp base thread to the exact external contour of the nubs, the reformed lamp base thread being shown in Fig. 9. As appears most clearly in Figures 4 and 5, the nubs 42 are arranged adjacent the lamp receiving end of the screw shell 12 so that the lamp base is firmly gripped immediately that it is inserted into the socket, this gripping action continuing thereafter throughout substantially the entire extent of the thread convolution. In consequence of the fact that this gripping action takes place at the outer end of the socket, it becomes impossible for the lamp to shift laterally or vibrate when it has been threaded into its socket, thereby insuring at all times a firm electrical connection between the center contacts of the lamp and socket. If desired, the socket casing 10 may be provided with the vertically extending internal ribs 44 which serve as supplemental spacers between the screw shell 12 and the casing 10. Provided in the base of the socket are a pair of internally threaded inserts 45 arranged to receive the ends of suitable securing elements (not shown), for securing the socket to a mounting member (also not shown).

It will be observed that in this particular socket the center spring contact 35 serves solely as an element for electrically connecting the center contact of the lamp with the terminal member 31, it being unnecessary to depend upon its resiliency to prevent the lamp from backing-out" of its socket, this latter tendency being eflectually precluded solely by the action of the lamp base gripping members 40. It will be further observed that the lamp socket as described is not only simple and inexpensive in construction but it is also efiicient, strong and durable in use.

It will be understood that various changes may be made from time to time without departing from the general spirit or principles of the invention, and it is accordingly intended to claim the said invention broadly, as wellas specifically, as indicated in the appended claims.

What is claimed as new and useful is:

1. In a lamp socket, in combination, an annular contact shell having an aperture formed in the side and adjacent the lamp-receiving end there of, a main body enclosing said shell, and a transversely flexed plate interposed between said shell and said body in the vicinity of said'aperture, said plate having free ends extending laterally to either side of said aperture and engaging said body and said plate being provided with a projection extending through said aperture for resiliently engaging the base of a lamp inserted into said socket.

2. In a lamp socket, in combination, a threaded contact shell having an aperture formedin the side and adjacent the lamp-receiving end thereof, an insulating casing enclosing said shell and provided with a plurality of internal vertically extending ribs for maintaining said shell and casing in spaced relation, a flexible plate arranged within the space formed between said shell and casing, the curvature of said plate'being normally 3. In a lamp socket, in combination, a threaded contact shell having oppositely disposed apertures formed in the upper portion of the thread con-1 volution, an insultating casing surrounding said shell and maintained in spaced relation with respect thereto, a pair of opposed flexible members interposed between'said shell and casing, the

ranged in abutting relation against said casing such that the intermediate portion thereof is resiliently urged against said shell; and studs secured to said members and projecting through said apertures into the interior of said shell'ior engaging opposite sides of a lamp base inserted .outer portions of each of said members being ar- I into said shell, the inner ends of said studs being each of a vertical cross-section of arcuate form and of a depth substantially equal to the pitch'of a standard lamp base thread the vertical curvature of said means being of greater radius than the radius of the corresponding curvature of a standard lamp base thread.

4. In a lamp socket, in combination, a threaded contact shell having oppositely disposed apertures formed therethrough, and spring-pressed means projecting through said apertures for frictionally engaging opposite sides of a lamp base threaded into said shell, the vertical curvature of said means being of greater radius than the radius of the corresponding curvature of a standard lamp base thread the pressure applied to said means being from a point located exteriorly of the contact shell.

5. In a lamp socket, in combination, a threaded contact shell arranged to receive a threaded lamp base therein, and spring-pressed means projecting laterally through an aperture formed in the wall of said shell and into the path of said lamp base, the projecting end of said means being of a convex curvature less than the corresponding concave curvature of the thread of said lamp base whereby when the latter is threaded into said shell said thread is reformed to correspond to the curvature of said projecting end.

6. In a lamp socket, in combination, an insulating body member having an opening in the side wall thereof communicating with an opening in the bottom thereof, a lamp base contact member secured to said body member, a terminal element operatively associated with said contact member and having a struck-out portion forminga loop through which the bared end of a conducting wire may be inserted, said wire being insertable through said bottom opening and being accessible,

for purposes of attachment to said terminal ele-' ment, through said side wall opening.

HERBERT J. GRAHAM. 

